What Our Forecast Says About The Race In Florida And Arizona

While the COVID-19 virus continues to dominate headlines, the Democratic presidential primary marches on - for the most part, at least. On Tuesday, four states vote, including some of the most delegate-rich states in the country. The main question now is just how much of an edge does former Vice President Joe Biden have in each contest, given his strong position overall. (Our model thinks he has a more than 99 percent chance of winning the majority of pledged delegates.) The results on Tuesday could affect how long Sen. Bernie Sanders stays in the race - and how soon Biden secures that delegate majority, and thus the nomination.

So here's a closer look at what our forecast has to say about the two Sun Belt states casting ballots on Tuesday: Florida and Arizona. (You can read about Tuesday's Midwestern contests, in Illinois and Ohio, here.)

Biden is favored to defeat Sanders by large margins in both Florida and Arizona. He has a greater than 99 percent chance of winning the most votes in Florida, according to our forecast, and a 98 percent chance in Arizona.

Let's look at Florida first. The Sunshine State is worth 219 pledged delegates, and Biden wins, on average, 68 percent of the vote there, versus just 27 percent for Sanders, per our forecast. A result like that would likely give Biden the bulk of Florida's 76 statewide delegates.

Florida's other 143 pledged delegates are apportioned according to how the candidates perform in each of the state's 27 congressional districts, but there's not much good news for Sanders at the district level either. Instead, Biden's large statewide edge is reflected, to varying degrees, in every district. His smallest average margin in any district is still a whopping 33 percentage points. And there are even a few districts where Sanders's forecasted vote share is only a few points above the 15 percent threshold needed to qualify for delegates - in other words, it's possible that Sanders will miss out on winning any delegates in a handful of Florida districts on Tuesday.

Biden should rack up Florida delegates - everywhere

Average forecasted vote share for the top two Democratic presidential candidates in Florida congressional districts, according to the FiveThirtyEight model as of 6 p.m. on March 15

Biden's three strongest districts - thanks to his overwhelming support from black voters - are all either majority or plurality African American. He projects to win at least 75 percent of the vote, on average, in the 5th Congressional District that stretches across northern Florida (including parts of Jacksonville and Tallahassee), as well as in the 20th and 24th Congressional districts in South Florida, stretching from parts of Palm Beach to Miami. But Biden also gets around 70 percent in fairly white and rural districts, such as the 1st and 2nd Congressional districts in the Florida Panhandle, owing to his solid showings among white voters in the South. Indeed, Sanders's weakness among black voters and southern whites makes him a particularly poor fit for Florida.

Sanders has performed better among Hispanic voters than Biden, but that will likely be less true in Florida, particularly in South Florida, where many Hispanics are Cuban Americans. As my colleagues Amelia Thomson-DeVeaux and Nathaniel Rakich wrote, Sanders's identification as a "democratic socialist" - and his refusal earlier this year to condemn former Cuban President Fidel Castro may be off putting to many Cuban Americans, who tend to be more anti-socialism given Cuba's socialist past.

Moving west across the southern U.S., Arizona doesn't look to be a Biden blow-out quite on Florida's level, but it still doesn't look all that competitive. Our forecast gives Biden a 49 in 50 (98 percent) chance of winning Arizona, leaving Sanders with only a 1 in 50 shot. Twenty-three of Arizona's 67 pledged delegates will be awarded based on the statewide vote share, and Biden wins an average of 58 percent compared to Sanders's 34 percent, according to our forecast.

The other 44 pledged delegates will come from each of Arizona's nine congressional districts. And as the table below shows, we expect the outcomes in these seats to look pretty similar, with Biden holding a 20-plus point advantage in each district. Still, there's no risk of Sanders missing the 15 percent threshold anywhere, unlike in Florida.

Biden leads in Arizona, but Sanders will win some delegates

Average forecasted vote share for the top two Democratic presidential candidates in Arizona congressional districts, according to the FiveThirtyEight model as of 6 p.m. on March 15

Biden has a sizable edge in both of Arizona's majority-Latino seats: the 3rd Congressional District that sits mostly southwest of Phoenix and runs along the U.S.-Mexico border, as well as the 7th Congressional District in Phoenix. And while that may be a little surprising because Sanders has been stronger among Latino voters than Biden thus far, it's important to remember that most primary voters in Arizona will be non-Hispanic white. There was no exit poll for the Democratic primary in 2016, but data from the Cooperative Congressional Election Study estimated that around 70 percent of the electorate was non-Hispanic white then.

Still, there's a chance that Sanders will do better in the seats with large Latino populations - a recent Mason-Dixon poll of only Latino voters in Arizona found Sanders narrowly ahead of Biden - but it's also possible that Biden's lead as the front-runner will eat into some of Sanders's support among Latinos. That poll was conducted in the days just after Super Tuesday, and Biden's grip on the nomination is considerably tighter now.

In short, Biden is a heavy favorite to win both of these states on Tuesday, likely by margins that will add to his already considerable delegate lead over Sanders. If Sanders is to remain at all competitive, he needs to do far better than the polls show in places like Florida and Arizona.

Confidence Interval: The 1st female president will be a Republican